This invention relates to vehicle safety belts and particularly to passive safety belt devices which are automatically applied across a vehicle occupant.
According to a known passive safety belt arrangement, one end of the belt is wound on an automatic winding spool adjacent the vehicle seat on the side of the seat away from the vehicle door. The other end of the belt is carried in a slide carriage which moves in a track attached to the frame of the vehicle adjacent the vehicle door. The slide carriage moves in the track between a restraining position, in which the belt is applied across a vehicle occupant in the seat, and a second release position in which the belt is lifted off the occupant. Under ordinary circumstances, the winding spool operates automatically to take up or pay out the belt as required by the movement of the carriage or the passenger. The winding spool is provided with an inertially operated locking device having an inertial mass which displaces and locks the winding spool when the vehicle undergoes sudden acceleration or overturns. Locking of the winding spool causes the devices to restrain the passenger thereby preventing serious injury.
There have been known prior art devices which include blocking devices for keeping the inertial locking mechanism from locking the belt winding spool under certain conditions. One such device, used in an arrangement wherein the safety belt is attached to the vehicle door at one end, prevents locking of the belt winding devices when the vehicle door is open. This prevents a condition wherein the the locked spool prevents opening of the vehicle door. Such devices, described in German Patent Publications Nos. 23 50 328 and 23 55 562, operate either by means of a mechanical lever connected to the door lock or by the use of an electrical door contact switch.
While safety belt devices of the type to which the present invention is applicable, wherein the belt is not attached to the vehicle door, are not likely to become jammed in a position which would prevent opening of the door, it is undesirable to have the winding spool locked in a manner which prevents removal of the safety belt to its passenger release position. Further, where the blocking device is activated by the vehicle door, there is substantial risk that a collision induced deformation of the vehicle door will cause a constant disengagement of the locking device thereby rendering the safety belt inoperative in the event of a subsequent collision.
It is therefore an object of the present invention to provide a new and improved passive safety belt device wherein the belt winding spool locking device is rendered inoperative except when the belt is in the passenger restraining position.